He laughs, reaching out to smack Castiel's ass with his hand. Right where it would jostle the plug. "You're going to feel me for days," he promises, stepping back far enough to be able to swing the flogger. The first stroke is light, a warning and getting a feel for the weight and the distance. Then he laid into Castiel properly, spreading the strokes out a bit so that some of them hit his shoulders and across his thighs, but most of them went across his ass.

When Sam got to twenty, he stopped with one last stroke across Castiel's ass before he moved forward, laying a hand over the reddened skin to feel the heat. And also to make certain there wasn't any bleeding. "What color, Cas?"